How to display tank transducer data

Zing

Zing

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I have 6 tanks on the boat and inherited from a previous owner, each has a level sensor with 4mA - 20mA standard industrial control outputs. They are now disconnected as the interface is broken.

I can buy programmable panel meters for them at a cost of £400 to £500, which seems overkill and a waste of limited panel space. Also it they don't allow calibration from a look up table, which would be the most accurate way to calibrate them. and for each tank to be separately calibrated as they are all different.

I wonder if there is be a better (and ideally cheaper) way? It would be good to put the data onto a NMEA bus, either 183 or N2K and then to read the data on my plotter or PC chart plotter, or maybe on a stand alone PC program. A clever display with a rotary selector switch may be an answer too, but I can't find one.
 
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First of all its 4 to 20mA current loop.

VDO have a fuel and water display which 4 to 20 mA input.

I have 3 fuel tanks and 2 water tanks with a single VDO display for each switched between each tank with a 2 or 3 position toggle switch for each set.
 
Thanks. Typo corrected. I could use two gauges as you suggest, or even one with a row of pushbuttons and they make some pretty displays now, but I suspect there is a better and more accurate way using NMEA maybe.
 
NMEA 2000 has one PGN 127505 «Fluid level»
Fluid Level contains an instance number, type of fluid, level of fluid, and tank capacity. For example the fluid instance may be the level of fuel in a tank or the level of water in the bilge. Used primarily by display or instrumentation devices.
Field # Field Description
1 Fluid Instance
2 Fluid Type
3 Fluid Level
4 Tank Capacity
4 Reserved Bits
Click to expand...
I have one calibrated sensor for fuel and one for water. But I’m not impressed be my Raymarine plotters display of the data. For fuel I can get volume in liters but water is only showing as % of capacity.
 
knuterikt said:
NMEA 2000 has one PGN 127505 «Fluid level»

I have one calibrated sensor for fuel and one for water. But I’m not impressed be my Raymarine plotters display of the data. For fuel I can get volume in liters but water is only showing as % of capacity.
Click to expand...
Which calibrated sensors do you use?
 
Zing said:
Thanks for that. I read the manual. It looks like it would work. It seems you need a Maretron programmer display to set it up. They are pretty expensive. Also it seems you can't calibrate it fully; you can only set the full and empty levels.
Click to expand...

I'm not suggesting it is the solution I would use, just that it would do what you would need. It is probably the only device on the market that would put 4-20mA on to NMEA2000, the fact it does 6 channels is a bonus!

Your primary problem is they have used 4-20mA senders, these are not generally used in leisure marine, hence the limited choice of interfaces.

If it was a local job,
I'd look at the MFD on board and check what NMEA2000 PGN's it will accept making sure it will even display gauge information!
Then, I'd either replace all the tank senders with resistive ones, probably from WEMA. That assumes the tanks have standard sender mounts in them.
Then you can select from a much wider range of NMEA2000 tank adaptors to choose from.

Or, I'd add an interface to each of the senders converting 4-20mA to 0-5vdc and use something like CZone, but again these need programming tools.

The other problem with the Maretron is you would be stuck with 4-20mA senders if one failed in the future.

there are ways of doing it, but as with everything that is not standard

Result
--------------
Time | Money

and all three are variable!
 
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